1. Technical Field
Embodiments of present invention relate to method for positioning a photoelectric conversion device, and a liquid ejecting apparatus that includes a photoelectric conversion device.
2. Related Art
An ink jet printer is known as an example of the liquid ejecting apparatus. The printer forms an image on paper by ejecting a printing liquid onto the paper. The printing liquid is an example of a liquid that is ejected from a liquid ejecting unit onto the paper. The printer includes a transport unit and the paper is an example of a medium which is transported a predetermined movement amount by a transport roller of the transport unit. Accordingly, the image in the transport direction of the paper is influenced by the precision of the movement amount of the paper or the precision with which the medium or paper is transported.
A printer may include a detection unit which detects the movement amount of the paper, and a transport control unit. An adjustment is performed by the transport control unit controlling the transporting of the paper based on a detection result of the detection unit such that the movement amount of the paper is a predetermined value. JP-A-2013-119439 discloses an example of such a printer. The detection unit included in the printer of JP-A-2013-119439 is provided with a light emitting unit which emits light that irradiates a rear surface of the paper, an optical member such as a lens which focuses the light which is reflected from the rear surface of the paper, and an imaging unit in which an imaging device is housed in a case. The imaging device acquires a paper surface pattern of the rear surface of the paper based on the light that is focused by the optical member.
The case of the imaging unit is generally formed integrally with a lens barrel member which houses the optical member and the imaging device, and a housing portion which houses the light emitting unit. The imaging unit is provided with transparent glass on a distal end of the housing portion. The transparent glass is disposed such that the center thereof is aligned with the optical axis of the optical member. The housing portion is attached to a medium supporting portion of the printer such that the detection window which is formed in the medium supporting portion is aligned with the transparent glass. The detection unit detects the movement amount of the paper based on the paper surface pattern of the rear surface of the paper which the imaging unit acquires an image of. In other words, movement amount of the paper detected by the detection unit is based on the image of the rear surface of the paper.
However, the precision of the image that is acquired by the imaging device that is housed in the lens barrel member is reduced by stray light. Stray light is generated light that is scattered at the inside wall of the lens barrel member and at the edge of the lens. In a positioning step of the imaging device in which the center position of the imaging device is aligned to the optical axis of the optical member based on an output signal of the imaging device, which is output according to the light with which the imaging device is irradiated, there is a concern that misalignment will increase when the precision of the image that is acquired by the imaging device is reduced. The scattered light can reduce the precision with which the image is acquired.
When the precision of the image that is acquired by the imaging device of the imaging unit is reduced or is deteriorated, for example by scattered light, there is a concern that the precision of the movement amount of the paper detected by the detection unit will be reduced. Note that, because the imaging unit that is mounted to the printer of JP-A-2013-119439 is not particularly made in consideration of the precision of the image that is acquired by the imaging device being reduced due to stray light in this manner, the imaging unit is considered to include the same problem as that described above.